Dictionary A B C D E F G H I J K L M N O P Q R S T U V W X Y Z chaos Chaos is the breakdown of predictability, or a state of disorder (cf Chaos Discussion, also Chaos is Everywhere Discussion). cipher Ciphers are codes for writing secret messages. Two simple types are shift ciphers and affine ciphers (cf Cryptography and Ciphers Discussion). complementary angles Two angles that have a sum of 90 degrees. class interval In plotting a histogram, one starts by dividing the range of all values into non-overlapping intervals, called class intervals, in such a way that every piece of data is contained in some class interval (cf Class Interval: Scale and Impression Discussion, Mean, Median and Mode Discussion, also Vertical Scale Discussion: Increase or Decrease?). coefficients The numbers in front of the letters in a mathematical expression, for example, in: 4d + 5t2 + 3s, the 4, 5, and 3 are coefficients for the d, t2, and s (cf Pascal's Triangle Discussion). combinatorics The science that studies the numbers of different combinations, which are groupings of numbers. Combinatorics is often part of the study of probability and statistics (cf Tables and Combinatorics Discussion). commutative property This property of both multiplication and addition states that you can rearrange the order of the numbers being added or reorder numbers being multiplied without changing the value of the expression. In mathematical terms, for all real numbers a and b, a+b=b+a and ab=ba. complex numbers One can think of them as an ordered pair of numbers. Complex numbers helped earlier mathematicians deal with the problem of taking the square root of a negative number. A complex number takes the form a + b*sqrt(-1), where a and b are real numbers (cf Two Variable Functions Discussion). concave up A curve is "concave up" when it is a concave shape, meaning curved like the inside of a bowl, with the two ends of the curve pointing up. (cf Gathering Information from Graphs Discussion). conditional probability Conditional probability is the probability of an event occurring given that another event also occurs. It is expressed as P(A/B). It reads "Probability of Event A on condition of Event B." P(A/B) = P(A and B)/P(B), where P(B) is the probability of event B and P(A and B) is the joint probability of A and B (cf Conditional Probability Discussion). congruent Two figures are congruent to one another if they have the same size and shape (cfRectangles and Squares Discussion). constant functions Functions that stay the same no matter what the variable does are called constant functions (cf Gathering Information from Graphs Discussion). constants In math, things that do not change: for example distance, volume, mass, are called constants. The things that do change are called variables (cf Gathering Information from Graphs Discussion). continuous graph In a graph, a continuous line with no breaks in it forms a continuous graph (cf Impossible Graphs Discussion). coordinate plane (Cartesian) A plane with a point selected as an origin, some length selected as a unit of distance, and two perpendicular lines that intersect at the origin, with positive and negative direction selected on each line. Traditionally, the lines are called x (drawn from left to right, with positive direction to the right of the origin) and y (drawn from bottom to top, with positive direction upward of the origin). Coordinates of a point are determined by the distance of this point from the lines, and the signs of the coordinates are determined by whether the point is in the positive or in the negative direction from the origin (cf From Graphs to Machines and Back Discussion). coordinates A unique ordered pair of numbers that identifies a point on the coordinate plane. The first number in the ordered pair identifies the position with regard to the x-axis while the second number identifies the position on the y-axis (cf Introduction To The Coordinate Plane and Coordinates Discussion). corresponding angles Two angles in the same relative position on two lines when those lines are cut by a transversal. cube A prism with six square faces. A B C D E F G H I J K L M N O P Q R S T U V W X Y Z